DUKE 

UNIVERSITY 


LIBRARY 


Digitized  by  the  Internet  Archive 

in  2016 


https://archive.org/details/brachiospongidae01beec 


MEMOIRS  OF  THE  PEABODY  MUSEUM  OF  YALE  UNIVERSITY. 

VOL.  II,  P'ART  I. 


BKACHIOSPONGIDBE: 

0 

% 

A 

MEMOIR 

ON  A 

GROUP  OF  SILURIAN  SPONGES. 

WITH  SIX  PLATES. 


BY 

CHARLES  EMERSON  BEECHER. 


NEW  HAVEN,  CONN.: 

PBINTED  FOE  THIE  MUSEUM. 

1 88  9. 


0 HR  f Ui 


H 


- 


v>  • ... 


■ . VS,  '■ 

, -■  r 

■ 

. . ...  . ' 

■ 


- h V ■ ■ • -r  ^ -v;: 


WM 

" ; -•  ‘ ■ ■ " ; • tf  • /.,;•*  fe  ■ .•*.**/  ''/> 

- V .•  • . ■,  ■•••  ■'  " . >>  ; Kg 

■ ",  v-  ' - 


v • ■ ; , ••  i i .*  *v  • •.<  >!  . \ ••  *v»  • 

— - ;r.->  / - 

‘ r;  ' - ■ ■ ■ ; ..  - 


. s 


; 

- - , - _ . ■ : . 

, . V •.  . r,  ■ : , •/'  ■'  • • • /»*•  - 

.•  • ' . * • • • - • ff  i«  - 1 


1 ' . 'j 


' - V-  S 


press,  of  Tuttle,  Morehouse  & taylor,  New  haven,  conn. 

■v'  • •*  " 7 -■  . 


- i,  - 


, 


, 

- 

. 


■'-T'ih  " 

«'r'- 


/■'  1 7 ' .■  \ ‘ ,r  _ 


V..  1 


- 

> t cv  Y\  ...  ^ ■ • ■ ■ 

. 

■ - ' ■ : .•  -'V'T.".  ■"  ' ; 


’/r  | 


,'j,;AVv^OO  .in' 

& M 


- 

J<  : ' 


•a ■■■■:: 


gjEvV  t 5 

..  -■  i' 


■ v - 


■ 

, • - ■ n ,■  s ’ 

• • 

' ' . ■ '-H  7 


, v'  v'j  - • 


, - 1 . 


' . *•  r • . • ■.  . ' '•  v-.f 


- 


, ■■■•  “ ■■  ■ V • ■' 

■ ;■  ■ - : ' " 1 " " 
-•  1/  -•••  > . 

1 ' M 


' 


v,  •'  • ■ ’ - . • 

v" 

■ 1 ■ 

■ ■ -•  . 


. ■ 

' 

;1  ,■  ; ■ . 


MEMOIRS  OF  THE  PEABODY  MUSEUM  OF  YALE  UNIVERSITY. 

VOL.  II,  PART  I. 


BRACHIOSPONG-ID  M: 


MEMOIR 

ON  A 

GROUP  OF  SILURIAN  SPONGES. 

WITH  SIX  PLATES. 


CHARLES  EMERSON  BEECHER. 


NEW  HAVEN,  CONN.: 

PRINTED  FOP?.  THE  RTTTSPHTIVE. 

1 8 8 9. 


BRACHIOSPONGID^E. 

(With  Six  Plates.) 

By  Charles  Emerson  Beecher. 


BRACHIOSPONGIA,  Marsh. 

These  sponges  were  made  known  as  early  as  1838,  and  were  the  first 
strictly  American  paleozoic  sponges  described.  The  systematic  position 
of  Brachiospongia,  however,  has  remained  hitherto  undetermined.  Pro- 
fessor Karl  A.  von  Zittel  placed  the  genus  provisionally  in  the  fatuity 
Euretidse,  Zittel,  under  the  order  Hexactinellida.  This  arrangement  was 
followed  by  Dr.  Gr.  J.  Hinde,  although  he  regarded  the  position  of  the 
genus  uncertain,  as  its  structure  was  unknown. 

The  basis  of  our  information  of  these  variable,  and  often  imperfectly 
preserved  fossils  must  rest  largely  upon  the  results  of  the  study  of  more 
recent  forms,  and  the  interpretation  of  the  fossil  must  be  in  the  same  terms 
used  for  the  living  organism. 

The  first  systematic  grouping  of  sponges,  based  upon  reliable  char- 
acters, was  worked  out  with  great  care,  in  Zittel’s  memoirs,  published 
during  the  years  1876-78.  All  subsequent  writers  have  accepted  the 
principles  which  he  established,  and  have  adopted  his  main  subdivisions. 


O ocho/’ 


4 


BRACHIOSPON  GIDaE. 


The  later  investigations  of  Dr.  G.  J.  Hincle  have  largely  supplemented  our 
knowledge  of  the  fossil  forms,  and  with  the  crowning  work  by  Dr.  F.  E. 
Schulze,1  on  the  recent  species  of  the  order  Hexactinellida,  the  paleontolo- 
gist can  readily  interpret  his  observations,  and  classify  the  various  species 
and  genera  which  preserve  the  main  features  of  their  structure. 

Histokical  account  of  Beachiospongia. 

1838. 

G.  Teoost.  Description  d’un  Nouveau  Genre  de  Fossiles.  (Mem.  Soc. 

Ge'ol.  France,  Vol.  Ill,  pp.  95,  96  ; PI.  XI,  figs.  8,  9,  10.) 

The  new  genus  described  in  this  paper  was  a cephalopod  (Conotubu- 
laria),  which  has  since  been  considered  as  a synonym  under  the  genus 
Orthoceras.  A new  species  of  Asaphus  (A.  megalopthalmus ) is  also  indicated 
and  figured.  The  paper  concludes  with  “ Description  d’un  fossile  repre- 
sent^ dans  la  pi.  XI,  fig.  8,  9,  10,”  where  an  account  is  given  of  a fossil 
which  is  at  once  recognized  as  Brachiospongia.  The  specimen  has  nine 
arms,  and  is  described  as  silicified.  Dr.  Troost  suggests  its  affinities  with 
sponges,  and  states  that  he  discovered  the  fossil  in  a limestone  occurring 
in  Davidson  County,  Tennessee.  Singularly,  no  name  was  proposed,  and 
apparently,  no  notice  has  been  taken  of  the  description  and  figures  in  any 
publication,  previous  to  Dr.  G.  J.  Hinde’s  Catalogue  of  the  Fossil  Sponges 
in  the  British  Museum,  1883. 

It  seems  more  than  probable  that  the  specimen  in  the  possession 
of  Dr.  Troost,  in  1838,  and  described  by  him,  is  identical  with  the  one 
which  was  made  the  type  of  Brachiospongia  roemerana , by  Professor 
0.  C.  Marsh,  in  1867,  and  is  now  illustrated  on  Plate  I of  the  present 
memoir.  The  evidence  is  based  upon  the  striking  resemblance  between 
this  example  and  the  figures  on  Plate  XI  of  Troost’s  paper.  The  general 
dimensions  agree  very  closely,  and  in  addition,  the  diameters  and  height 
of  the  neck,  and  the  length  of  the  longest  arm  are  the  same.  Besides 
having  a like  number  of  arms,  and  agreeing  in  size,  a more  marked 

1 Report  on  the  Hexactinellida  collected  by  H.  M.  S.  Challenger  during  the  years 
1873-1876.  Zoology,  vol.  xxi,  1887. 


RRACHIOSPONGIDiE. 


5 


resemblance  may  be  traced,  if  the  type  of  B.  rmmerana  is  placed  in  a 
slightly  inclined  position,  which  is  the  one  naturally  assumed  on  account 
of  the  imperfection  of  the  lower  portion,  and  the  arms  then  compared 
seriatim  in  respect  to  direction,  length,  and  size.  It  must  be  assumed, 
however,  that  the  lithograph  was  made  without  reversing  the  drawings, 
and  that  the  specimen  appears  reversed  on  the  plate.  The  inference  is 
supported  by  the  fact  that  the  shadows  on  all  the  figures  are  manifestly 
on  the  wrong  side. 

A comparison  under  these  conditions  shows  that  the  widest  divergence 
between  any  two  arms  is  adjacent  to  the  longest  and  unbroken  one.  The 
latter  arm  is  oblique  to  the  longitudinal  diameter  of  the  osculum,  and  the 
three  shortest  broken  arms  are  adjacent  to  it,  and  are  situated  on  the  side 
opposite  the  greatest  interbrachial  space.  The  side  view  offers  similar 
points  for  comparison,  if  the  specimen  is  placed  in  the  proper  position.  It 
should  also  be  noted,  that  this  individual  shows  a greater  elevation  of  the 
neck,  and  of  the  arms  near  their  origin,  than  has  been  observed  in  any 
other. 

The  history  of  the  type  specimen  is  somewhat  obscure,  but  nevertheless 
furnishes  additional  proof  in  support  of  its  identity  with  the  one  described 
by  Troost.  According  to  the  best  evidence  at  present  attainable,  it  was  in 
the  possession  of  Dr.  Yandell  in  1855,  who  at  that  time  was  custodian  of  a 
portion,  at  least,  of  the  Troost  collection.  Rev.  H.  C.  Hovey  obtained  the 
specimen  in  exchange,  and  subsequently  transferred  it  to  Professor  0.  C. 
Marsh,  who,  after  describing  it  in  1867,  presented  it  to  the  Museum  of 
Yale  College. 

1858. 

D.  D.  Owen.  Kentucky  Geological  Survey,  Vol.  II,  p.  111. 

In  his  report  on  the  geology  of  Franklin  County,  Owen  refers  to  the 
principal  external  features  of  these  sponges,  and  proposes  for  them  the 
specific  name  cligitata,  which  he  places  under  the  genus  Scgphia,  Oken. 
The  locality  of  their  occurrence  is  described,  and  the  geological  horizon  is 
referred  to  a position  near  the  middle  of  a detailed  section  of  Lower 
Silurian  strata,  at  Frankfort,  Ky. 


6 


BRACHIOSPON  GIDAE. 


1862. 

R.  Owen.  Indiana  Geological  Survey,  1859-60,  pp.  362,  363,  fig.  1. 

A very  imperfect  specimen  is  figured,  accompanied  by  a brief  descrip- 
tion, in  which  the  name  is  changed  to  Syphonia  digitata.  In  a letter 
written  to  Professor  Marsh,  in  1867,  Professor  Owen  states  that  the  altera- 
tion in  the  name  was  through  inadvertence. 

1865. 

H.  A.  Ward.  Eighteenth  Annual  Report  New  York  State  Cabinet  of 
Natural  History,  p.  29,  fig.  4. 

A wood-cut  of  an  eleven-armed  specimen  is  given,  and  referred  to 
“ Amorphozoum  ? ” The  same  figure  is  reproduced  by  Professor  Ward, 

under  the  name  “ Amorphospongia ,”  in  his  “Catalogue  of  Casts  of 

Fossils,”  published  in  1866.  This  specimen  was  made  the  type  of 
Brachiospongia  lyoni , by  Professor  Marsh  in  1867. 

1867. 

0.  C.  Marsh.  American  Journal  of  Science,  2d  Series,  Yol.  XLIY,  p.  88. 

In  this  preliminary  paper,  the  genus  Brachiospongia  is  first  proposed 
and  described,  and  the  species  B.  roemerana  and  B.  lyoni  are  named 
provisionally.  B.  roemerana  was  proposed  for  a nine-armed  specimen 
which  now  appears  to  be  the  original  type  of  Troost’s  description  and 
figures.  The  name  B.  lyoni  was  given  to  a specimen  having  eleven  rays, 
then  in  the  collection  of  S.  S.  Lyon.  Photographs  and  lithographic  figures 
of  the  type  specimen  B.  roemerana  were  made  at  this  time,  but  copies  of 
the  former  alone  were  distributed. 

1868. 

0.  C.  Marsh.  Proceedings  of  the  American  Association  for  the  Advance- 
ment of  Science,  p.  160. 

A paper  was  read  at  the  sixteenth  meeting  of  the  Association,  held  at 
Burlington,  Vt.,  “ On  some  new  Fossil  Sponges  from  the  Lower  Silurian.” 
In  the  published  volume  of  the  proceedings,  the  title  only  of  this  paper 
appears. 


BRACHIOSPONGIDiE. 


7 


1874. 

H.  C.  Hovey.  Transactions  Kansas  Academy  of  Science,  pp.  344,  345, 
figs.  1,  2.  Republished  in  the  Scientific  American,  pp.  387,  388,  figs. 
1,  2,  June,  1875. 

An  incomplete  historical  review  is  presented  of  the  published  notices 
of  Brachiospongia,  beginning  with  the  account  by  D.  D.  Owen,  in 
1858.  A wood-cut  of  the  type  of  B.  rcemerana , made  from  one  of  the 
photographs  distributed  by  Professor  Marsh,  and  a figure  of  a specimen 
referred  to  B.  lioveyi  (Marsh),  first  appear  in  this  publication.  The  name 
B.  lioveyi  was  proposed  for  an  example  with  twelve  arms,  and  was 
announced  in  the  paper  read  by  Professor  Marsh,  before  the  American 
Association.  The  specimen  figured,  which  was  not  the  type,  is  an  abnor- 
mal individual  of  B.  digitata,  in  which  the  arms  have  been  developed 
spirally  about  the  axis.  A strict  enumeration  of  the  partially  and  fully 
grown  arms  indicates  fifteen  as  the  number,  but  the  neck  is  imperfect,  and 
there  were  probably  more  in  the  entire  specimen. 

Subsequent  notices  of  these  fossils  are  mainly  of  the  character  of 
references,  and  include  the  following  : 

1877. 

Joseph  LeConte.  Elements  of  Geology,  p.  302,  fig.  290.  ( B . rcemerana.) 
S.  A.  Miller.  The  American  Palaeozoic  Fossils,  p.  42.  ( B . digitata , 

B.  lyoni , B.  rcemerana.) 

1878. 

K.  A.  Zittel.  Handbuch  der  Paheontologie,  Band  1,  p.  173.  ( Brack - 

iospongia.) 

1880. 

F.  Rcemer.  Lethsea  Geognostica,  1 Th.,  p.  319,  fig.  61.  (B.  rcemerana.) 

1883. 

G.  J.  Hinde.  Catalogue  of  the  Fossil  Sponges  in  the  Geological  Depart- 

ment of  the  British  Museum,  p.  102.  (B.  digitata  = B.  rcemerana  and 

B.  lyoni.) 


8 


RRACHIOSPONGID^E. 


Acknowledgments. 

The  abundance  and  richness  of  the  material  which  has  been  placed  at 
my  disposal  is  due  to  the  long  continued  efforts  of  Professor  0.  C.  Marsh, 
who  for  several  years  secured  all  the  specimens  found  at  the  principal 
locality.  It  was  the  original  intention  of  Professor  Marsh  to  publish  a 
memoir  upon  the  genus  Brachiospongia,  as  soon  as  the  completeness  of 
the  material  should  warrant  it ; but  the  development  of  his  researches  in 
the  fossil  vertebrate  fields  of  the  Western  States  and  Territories  soon 
reached  such  proportions,  and  became  so  important,  as  to  preclude  the 
carrying  out  of  his  original  purpose.  The  publication  of  this  memoir  in 
its  present  form  is  also  due  to  the  kind  liberality  of  Professor  Marsh. 

I wish  to  express  my  obligation  to  Mr.  Moritz  Fischer,  of  the 
Kentucky  Geological  Survey,  for  the  privilege  of  examining  and  figuring 
a fine  twelve-armed  specimen  belonging  to  the  State  Museum,  and,  also, 
for  courtesies  shown  me  during  a recent  visit  to  the  region  where  these 
fossils  have  been  obtained. 

The  collections  have  been  considerably  enriched  through  the  efforts 
of  Mr.  E.  C.  Went,  of  Frankfort,  Ky.,  in  the  discovery  of  a new  locality 
yielding  a number  of  interesting  examples  occurring  in  situ,  and  furnishing 
the  first  definite  knowledge  as  to  their  true  position  in  the  geological  series. 

Rev.  H.  C.  Hovey,  of  Bridgeport,  Conn.,  has  kindly  given  me  an 
opportunity  to  study  several  specimens  in  his  cabinet,  and  has  com- 
municated important  historical  points.  He  first  systematically  collected 
Brachiospongia,  and  observed  the  geographical  distribution  of  the  genus. 
A number  of  the  specimens  in  the  Yale  University  Museum  were  obtained 
through  his  researches. 

Geological  Position. 

The  precise  horizon  of  the  strata  furnishing  Brachiospongia  has  been 
uncertain.  Hitherto,  all  writers  have  agreed  in  referring  them  to  the 
Silurian,  the  particular  beds  being  unknown.  Rev.  H.  C.  Hovey  placed  them 
in  the  Birdseye  limestone.1  None  of  the  specimens,  however,  present  any 


Trans.  Kansas  Acad.  Sci.,  p.  344,  1874. 


BRACHIOSPONGIDJE. 


9 


evidence  of  having-  come  from  that  horizon,  and  all  the  known  localities 
furnishing  Brachiospongia  are  at  some  distance  from  exposures  of  the 
Birdseye,  and  at  a much  higher  level.  A single  example  was  found  in  a 
loose  piece  of  rock,  by  Mr.  Moritz  Fischer,  at  Benson  Station,  Franklin 
County,  which  was  apparently  derived  from  strata  belonging  to  the  middle 
of  the  Trenton  series.  So  far  as  known,  this  is  the  lowest  horizon  at  -which 
these  fossils  have  been  observed.  At  the  famous  locality  on  Benson  Creek, 
about  three  miles  above  Benson  Station,  where  nearly  all  the  specimens 
first  discovered  were  obtained,  no  accurate  determination  of  their  position 
could  be  made,  as  they  were  found  loose  in  the  debris  on  the  hillsides, 
and  on  the  banks  and  bed  of  the  creek.  The  same  observations  apply 
to  the  locality  near  Bridgeport,  Franklin  County.  At  Cedar  Run,  in  an 
exposure  discovered  by  Mr.  E.  C.  Went,  of  Frankfort,  Brachiospongia 
is  found  in  place,  and  its  true  horizon  and  associated  fossils  have  been 
determined. 

The  beds  consist  of  a fine  cherty  nodular  limestone  lying  above  the 
horizon  of  Orthis  borealis,  which  has  been  considered  as  the  upper  member 
of  the  Trenton.  They  are  succeeded  by  the  lower  beds  of  the  Hudson 
group  with  their  abundant  and  characteristic  fossils.  The  adjacent  lime- 
stones are  without  beds  of  chert,  and  are  coarser  grained,  so  that  the  rocks 
containing  Brachiospongia  are  easily  recognized. 

With  this  information,  the  sponge  horizon  was  traced  over  a consider- 
able extent  of  territory,  and  connected  with  the  other  localities  at  which 
Brachiospongia  occurs.  It  was  found  that  with  the  exception  of  the 
single  specimen  from  the  Middle  Trenton,  at  Benson  Station,  all  the 
localities  in  Franklin  County  were  at  the  same  horizon.  Similar  beds  cap 
the  Trenton  at  Lexington,  Ky. 

Under  the  description  of  B.  digitata , mention  is  made  of  a specimen 
from  the  Middle  Hudson  of  Spencer  County,  Ivy.,  which  presents  several 
points  of  difference  from  the  ordinary  form,  both  in  its  general  characters, 
and  condition  of  preservation.  As  a whole,  however,  this  species  has  a 
comparatively  limited  vertical  range,  and  its  occurrence  is  of  geological 
importance. 


3 


10 


BRACIIIOSPONGID^E. 


On  account  of  the  faunal  and  lithological  similarity  between  the 
Trenton  and  Hudson  groups  in  central  Kentucky,  the  horizon  of  B.  digitata, 
taken  in  connection  with  the  character  of  the  rock  and  associated  fossils, 
is  an  important  one,  as  furnishing  a definite  and  easily  recognizable  bed 
separating  the  two  formations.  The  Utica  Slate  is  absent  in  this  region, 
and  without  more  precise  information,  it  may  be  desirable  to  correlate 
with  it  the  Brachiosponge  beds,  in  which  case  the  latter  would  represent  a 
synchronous  deposit,  although  physically  different,  from  its  sedimentation 
in  deeper  waters,  probably  at  some  distance  from  the  shore  line. 

Associated  Fossils. 

Under  the  microscope,  the  rock  is  seen  to  be  composed  of  the  finely 
comminuted  testaceous  remains  of  Crustacea  and  mollusca,  mingled  with 
some  argillaceous  and  silicious  material. 

In  general,  the  beds  are  nearly  barren  of  fossils,  and  close  scrutiny 
reveals  but  a meager  fauna.  The  species  which  have  been  observed  are 
given  in  the  following  list : 

1.  Brachiospongia  digitata,  Owen.  Rare. 

2.  Strobilospongia  aurita,  Beecher.  Rare. 

3.  ? Strobilospongia  tuberosa,  Beecher.  Rare. 

4.  Root  tufts  (basalia)  of  sponges.  Common. 

5.  Hindia  parva,  Ulrich.  Common. 

6.  An  undescribed  genus  and  species  of  sponge.  Rare. 

7.  Diplograptus  putillus,  Hall.  Common. 

8.  Monticulipora  (fragments).  Rare. 

9.  Arabellites  cornutus,  Hinde.  Common. 

10.  Arabellites  sp.  Common. 

11.  Eunicites  sp.  Common. 

12.  Cyphaspis  (fragment).  Rare. 

13.  Beyrichia  chambersi,  S.  A.  Miller.  Rare. 

14.  Leperditia  sp.  Rare. 

15.  Leperditia  sp.  Rare. 


BRAOHIOSPONGIDvE. 


1 1 


16.  Zygospira  modesta,  Say.  Common. 

17.  Orthis.testu  din  aria,  Dolman.  Rare. 

18.  Tellinomya  obliqua,  Hall  Rare. 

19.  Cleidophorus  fabula,  Hall.  Rare. 

20.  Cyclora  minuta,  Hall.  Common. 

21.  Microceras  inornatum,  Hall.  Common. 

22.  Bellerophon  sp.  Rare. 

23.  Theca  parviuscula,  Hall.  Common. 

24.  Conularia  trentonensis,  Hall.  Rare. 

It  will  be  noticed  that  the  only  common  fossils  are  silicious  sponges, 
graptolites,  jaws  of  annelids,  Zygospira  modesta , and  the  minute  forms  of 
gastropods,  pteropods,  and  lamellibranchs.  The  Bellerophon,  Conularia, 
and  Theca  represent  pelagic  types,  and  the  remaining  forms,  not  micro- 
scopic, are  so  sparsely  distributed  that  they  were  probably  transported 
specimens,  or  at  least  did  not  flourish  where  found. 

The  Brachiospongia  are  in  their  natural  position  in  the  rock,  and 
evidently  were  buried  without  having  been  removed  from  their  original 
bed.  The  presence  of  the  numerous  masses  of  filamentous  spicules,  or 
basalia,  may  be  explained  by  their  having  originally  grown  in  the  soft 
mud  of  the  sea  bottom,  and  thus  were  protected,  while  the  exposed  cups 
of  the  sponges  would  be  subject  to  dissolution  and  destruction  unless 
previously  covered. 

Condition  of  Preservation. 

The  spicules  of  the  dermal  and  gastral  surfaces  are  usually  replaced 
by  calcite,  and  the  parenchyma  of  the  sponge  is  commonly  filled  with 
silica  Previous  to  the  process  of  mineralization,  the  spicules,  pores,  and 
interior  canals,  in  many  specimens,  were  enveloped  in  a thin  film  of 
peroxide  of  iron,  and,  although  the  invasion  of  silica  and  calcite  has 
involved  the  entire  space  occupied  by  the  organism,  this  film  now  serves 
to  differentiate  the  various  structures,  so  that  a satisfactory  study  may  be 
made  of  their  leading  features.  Many  of  the  more  minute  and  delicate 
spicular  membranes  are  probably  destroyed. 


12 


BR  ACIIIOSPON  GIDaE. 


It  has  been  shown  by  Dr.  G.  J.  Hincle  (Cat.  Foss.  Sponges,  p.  7),  that 
very  few  of  the  silicious  sponges  are  preserved  as  fossils  in  their  original 
condition,  and  that  a replacement  of  the  spicules  by  crystalline  calcite 
is  of  very  common  occurrence.  Even  in  a silicified  fossil  sjDonge,  the 
silex  is  not  in  its  original  state,  but  has  been  altered  or  replaced  by  silica 
of  a different  condition. 

The  majority  of  the  specimens  of  Brachiospongia  in  the  collections 
have  been  weathered  out  of  the  rock,  and  are  represented  as  silicified 
casts.  Owing  to  the  usual  exemption  of  the  dermalia  from  silicification, 
the  superficial  structures  are  not  preserved  in  weathered  examples,  nor  in 
specimens  which  have  been  freed  with  acids.  The  exposed  surface  of 
these  casts  shows  merety  the  extent  of  the  process  in  the  parenchyma, 
and  the  inequalities  in  its  distribution.  In  rare  cases,  the  dermal  skeleton 
has  been  silicified,  and  its  features  obliterated,  except  the  large  hypo- 
dermal  pentacts,  which  are  represented  by  numerous  papillae  on  the 
surface. 

The  first  alteration  of  the  original  colloid  silica  of  the  sponge  was, 
apparently,  to  calcite,  which  also  filled  many  of  the  interior  canals,  and, 
with  few  exceptions,  destroyed  the  axial  canals  of  the  spicules.  The 
subsequent  invasion  of  the  silica  and  partial  solution  of  the  calcite  have,  in 
some  instances,  separated  and  enclosed  the  calc  rhombs,  and  such  specimens 
when  weathered  now  exhibit  rhombic  cavities  in  the  silica.  Ordinarily, 
however,  the  calcite  has  been  simply  replaced  by  silex  in  the  form  of 
chalcedony,  except  in  some  of  the  larger  cavities  which  are  incrusted  with 
quartz  crystals. 

In  order  to  preserve  and  study  the  dermalia  and  gastralia,  it  is 
necessarv  to  secure  specimens  more  or  less  enveloped  in  the  matrix,  and 
to  uncover  them  with  instruments.  The  limiting  structures  may  be  further 
exposed  by  the  use  of  caustic  potash,  which  removes  much  of  the  argilla- 
ceous limestone  filling  the  pores. 


BRACHIOSPONGIDaE. 


13 


Systematic  Position. 

Class  SPONGIA. 

Order  Hexactinellida,  0.  Schmidt. 

Suborder  Lyssacina,  Zittel. 

Family  Brachiospongid^e,  nobis. 

Dermalia  forming  a quadrate  mesh,  in  which  are  immersed  large 
tree  pentacts,  or  modified  hexacts.  Parenchyma  thick,  with  large  free 
hexacts,  and  more  or  less  cylindrical  canals,  the  outer  ends  of  which  are 
covered  with  the  dermal  mesh. 

Including  the  genera, 

Brachiospongia,  Marsh. 

Strobilospongia,  nobis. 


Genus  Brachiospongia,  Marsh,  1867. 

(Am.  Jour.  Sci.,  2d  Ser.,  Vol.  XLIY,  p.  88.) 

[Type  Scyphia  cligitata,  D.  D.  Owen.] 

Sponge  in  the  form  of  a broad  cup  or  vase,  with  a row  of  projecting 
processes  or  arms  around  the  periphery  of  the  base,  and  into  which  the 
gastral  cavity  is  extended.  Osculum  large,  not  operculate.  Afferent  and 
efferent  canal  system  well  developed. 

Dermal  skeleton  composed  of  a fine  network  of  spicules,  in  which 
are  immersed  large  pentacts  with  the  proximal  rays  penetrating  the 
parenchyma.  Gastralia  large  and  free.  The  observed  parenchymalia 
consist  of  hexacts  which  are  sometimes  variously  modified.  Supported  on 
the  sea  bottom  by  the  peripheral  arms  and  broad  base  ; not  anchored  by 
bundles  of  spicules. 


4 


14 


BRACHIOSPONGIDJE. 


Strobilospongia,  gen.  nov. 

(From  the  resemblance  to  the  “Strobila”  stage  of  Aurelia,  and  from  the  twisted  base.) 

[Type  Strobilospongia  tuberosa,  nobis.] 

Sponge  cyathiform  or  globose,  with  more  or  less  concentric  rows  of 
lobes  or  lobed  expansions,  on  the  surface.  Anchored  to  the  sea  bottom  by 
means  of  massive  bundles  of  filamentous  spicules  (basalia)  proceeding 
from  the  interior  of  the  base  of  the  cup.  The  bundle  of  basalia  is  well 
defined  at  its  origin,  and  does  not  merge  into  the  tissues  of  the  sponge. 
The  spicular  structure  of  the  parenchyma,  so  far  as  observed,  agrees  with 
Brachiospongia.  Both  the  known  species  show  numerous  cruciform 
spicules  on  the  surface,  but  they  are  so  obscured  b}7  silicification  that 
their  detailed  form  and  relations  cannot  be  ascertained.  Smaller  spicules 
and  traces  of  a continuous  dermal  mesh  are  also  imperfectly  indicated. 

Any  systematic  division  of  paleozoic  sponges  into  orders  and  families 
is  necessarily  incomplete  and  unsatisfactory.  The  structures  are  but 
partially,  and  often  not  at  all  preserved,  and,  therefore,  the  data  for  a 
settled  classification  are  to  a large  degree  wanting.  It  is,  however,  of 
importance  to  give  the  geological  distribution  of  the  paleozoic  Hexacti- 
nellida,  and  this  is  done  in  the  table  on  page  16.  With  it  is  introduced 
a grouping  of  the  genera,  which  has  in  part  been  advanced  by  previous 
writers. 

The  family  Euretidse,  into  which  many  of  these  forms  were  originally 
placed,  has  since  been  restricted  by  Schulze  and  von  Lendenfeld  to  genera 
agreeing  more  closely  with  Eurete.  The  family  Pollakkke  is  probabl}7  not 
a natural  one,  and  it  is  now  a convenient  receptacle  for  genera  of  doubtful 
affinities. 

Etydnoceras  (=  Dictyophyton,  Hall)  and  allied  genera  are  well  char- 
acterized by  transverse  and  longitudinal  bundles  of  long  ra}7ed  spicules, 
which  divide  the  surface  into  squares  generally  arranged  in  fours,  and  by 
the  absence,  so  far  as  known,  of  a fused  dictyodermal  layer.  The 


BRACHIOSPONGIDiE. 


15 


parenchyma  is  also  comparatively  thin.  Professor  James  Hall  has 
proposed  the  family  Dictyospongidse  to  include  genera  possessing  these 
features.  The  group  appears  to  be  a well-founded  and  natural  one,  and 
belongs  to  the  suborder  Lyssacina.  In  addition,  Astylospongia  was 
removed  from  the  Hexactinellida,  by  Zittel,  in  1884,1  so  that  it  is  now 
significant  that  no  paleozoic  sponges  are  known,  which  can  with  certainty 
be  referred  to  the  suborder  Dictyonina. 

This  fact  may  have  an  important  bearing  upon  the  phylogeny  of  the 
suborders.  As  stated  by  Schulze,  either  the  Dictyonine  forms  have  been 
derived  from  the  Lyssacine  by  fusion  of  the  spicules,  or  both  suborders 
have  been  derived  from  a primitive  form  by  gradual  and  parallel  division. 
At  present,  all  the  known  paleozoic  hexactinellids  appear  to  belong  to  the 
Lyssacina.  The  suborder  is  represented  by  numerous  and  diverse  species, 
and  seems  to  have  reached  its  maximum  development  previous  to  the 
appearance  of  true  Dictyonina. 

There  are  several  genera  of  fossils  in  the  earliest  formations,  which 
have  as  yet  yielded  but  scant  evidences  as  to  their  proper  relations. 
Among  these  may  be  mentioned  the  genera  Calathium,  Billings ; Trachyum, 
Billings ; Spirocyathus,  Hinde ; and  Trichospongia,  Billings. 

A summary  of  the  distribution  of  the  genera  as  presented  in  the 
following  table  shows  that  the  rocks  of  the  Cambrian  (Taconic)  system 
have  furnished  two  genera  which  have  not  been  found  in  any  of  the 
succeeding  formations.  From  the  Silurian,  twelve  genera  are  recorded, 
seven  of  which  are  peculiar  to  the  system,  while  four  pass  into  the 
Devonian,  and  one  of  these  continues  into  the  Carboniferous.  The 
Devonian  has  afforded  but  one  genus  peculiar  to  it,  and  the  other  four 
cited  are  found  also  in  earlier  or  later  formations. 


1 Neues  Jakrbuck  fur  Mineralogie,  etc.,  1884,  Bd.  ii,  pp.  75-80,  Taf.  i,  ii. 


16 


BRAOHIOSPONGIDJE. 


Distribution  of  Paleozoic  Hexactinellida. 


Suborder  Lyssacina,  Zittel. 


Family  Dictyospongidje,  Hall. 

Protospongia,  Salter 

Cyathophycus,  Walcott 

Hydnoceras,  Conrad 

Ectenodictya,  Hall 

Plectoderma,  Hinde 

Lyrodictya,  Hall 

Thamnodictya,  Hall 

Phragmodictya,  Hall 

Cleodictya,  Hall 

Physospongia,  Hall 

Uphantaenia,  Vanuxem 

Family  Brachiospongid^e,  Beecher. 

Brachiospongia,  Marsh 

Strobilospongia,  Beecher 

Family  Pollakid^e,  Marshall. 

Hyalostelia,  Zittel 

Holasterella,  Carter 

Leptomites,  Walcott 

Astroconia,  Sottas 

Amphispongia,  Salter 

Acanthinella,  Hinde 

Family  Monakid.e,  Marshall. 

Astrseospongia,  JRcemer  

Family  Receptaculitid^e,  Hinde. 

Receptaculites,  HeFrance 

Ischadites,  Murchison 

Acanthoconia,  Hinde  


Cambrian. 

(Taconic.) 

Silurian. 

Devonian. 

Carbonifer- 

ous. 

• 

• 

• 

• 

— 

• 

• 

• 

— 

m m 

— 

• 

• 

• 

— 

• 

— 

• 

• 

• 

• 

— 

• 

• 

• 

— 

• 

• 

• 

— 

• 

• 

• 

— 

• 

• 

• 

— 

• 

• 

• 

• 

— . 

• 

? 

• 

• 

• 

• 

• 

• 

— 

— 

• 

• 

• 

• 

— 

• 

• 

• 

— 

• 

• 

• 

• 

• 

— 

• 

. 

. 

— 

— 

• 

• 

• 

• 

2 

12 

5 

10 

BRACHIOS  PONGID^E. 


17 


Variety  and  habitat  of  the  Paleozoic  Hexactinellida. 

In  a review  of  the  paleozoic  hexactinellid  fauna,  more  than  twenty 
genera  must  be  considered,  all  of  which  probably  belong  to  the  sub- 
order Lyssacina.  The  diversity  of  form  and  degree  of  specialization  in 
these  ancient  sponges  seem  to  be  even  greater  than  is  exhibited  among  the 
recent  species.  From  such  simple  cup-shaped  forms  as  Protospongia  and 
Cyathophycus,  there  is  a regular  gradation  to  the  angular  and  nodose 
Hydnoceras,  with  the  closely  allied  genera  Lyrodictya,  Cleodictya,  Physo- 
spongia  and  others  belonging  to  the  family  Dictyospongidee,  including, 
also,  the  wonderful  basket  disk  of  Uphantsenia.  Hyalostelia  represents 
the  enormous  root  spicules  of  an  otherwise  unknown  form.  Astrseospongia 
has  the  form  of  a compact  concavo-convex  disk.  Brachiospongia  with  its 
fingered  cup,  and  the  elaborate  Strobilospongia  with  its  solid  bundles  of 
anchor  spicules,  and,  finally,  the  Receptaculites,  with  no  recent  repre- 
sentatives either  in  form  or  structure,  exhibit  the  wonderful  develop- 
ment of  the  Hexactinellida  during  paleozoic  time. 

Altogether,  the  facts  point  to  the  culmination  of  the  Lyssacina  at  this 
period. 

The  recent  Hexactinellida  are  characteristic  deep-sea  types,  ranging 
from  a depth  of  ninety-five  fathoms  to  abyssal  regions.  In  a study 
of  the  paleozoic  forms,  it  is  interesting  and  important  to  determine,  if 
possible,  the  conditions  under  which  these  sponges  flourished.  Deep  sea 
investigation  tends  to  show  that  the  present  abyssal  oceanic  areas  and 
continental  masses  are  of  great  antiquity,  and,  consequently,  that  we  can 
have  but  limited  areas  and  localized  horizons  representing  deposition 
below  the  100-fathom  line.  Also,  it  has  been  shown  that  detrital  sedimen- 
tation almost  ceases  below  100  fathoms,  and  any  organisms  found  in  such 
formations  must  have  lived  in  areas  of  less  depth. 

The  evidence  furnished  by  observations  on  many  of  the  paleozoic 
hexactinellids  shows  that  although  occurring  in  groups  of  strata  often  con- 
taining an  abundant  fauna,  yet  the  particular  beds,  or  layers,  preserving 
the  sponges  in  their  greatest  perfection  and  abundance  are  comparatively 


5 


18 


BR  ACHIOSPON  GID  AS. 


barren  of  other  organisms.  In  some  cases,  they  must  have  thickly  covered 
the  sea  bottom.  The  Hydnoceras  tuberosum  from  Steuben  County,  N.  Y., 
occurs  in  countless  numbers,  at  several  limited  horizons,  in  a fine  grained 
and  at  times  argillaceous  sandstone.  It  is  rarely  associated  with  specimens 
of  crinoids  and  brachiopods.  Hydnoceras  prisma ticum  occurs  under  similar 
conditions.  Cyathophycus  reticulatus  is  found  also  in  great  numbers  on  the 
slabs  of  Utica  Slate,  from  Holland  Patent,  N.  Y.  In  Bkachiospongia, 
it  is  shown  that  the  associated  fossils  include  pelagic  species  and  others 
not  incompatible  with  a deep  water  habitat.  Barely  are  other  organisms 
associated  with  these  sponges,  although  the  conditions  were  evidently  such 
as  would  have  preserved  them.  The  occurrence,  too,  of  these  delicate  lace 
sponges  in  so  great  abundance  and  in  an  unbroken  state  shows  that  the 
waters  were  tranquil,  and  that  they  were  removed  from  active  physical 
changes. 

It  seems  reasonable  to  suppose  that  the  most  characteristic  and 
permanent  of  the  deep  sea  types  were  among  the  first  to  remove  from  the 
littoral  zone,  and  that  they  were  the  earliest  to  develop  features  adapted  to 
a deep  sea  existence.  In  many  organisms,  the  retention  of  brilliant  colors 
and  mimicral  characters  common  among  littoral  forms  shows  that  they  have 
migrated  from  the  shores  to  a deep  water  habitat  without  developing  into 
perfect  harmony  with  the  environment,  and  that  they  are  comparatively 
recent  additions  to  the  deep  water  fauna. 

On  the  contrary,  many  of  the  deep  sea  genera  have  lost  their  littoral 
features,  together  with  many  morphological  and  chromatic  specializations, 
and  are  in  accord  with  their  surroundings.  Hence,  the  species  within  the 
present  limits  of  these  genera  are  strictly  a development  under  deep  water 
conditions,  and  to-day  have  no  littoral  representatives.  Only  in  remote 
time,  or  ancient  deposits,  are  related  or  ancestral  forms  found,  exhibiting 
a shallow  water  distribution. 

The  recent  hexactinellid  and  lithistid  sponges  are  among  the  most 
extensive  groups  which  are  peculiar  to  the  deeper  zones.  Their  abundance 
and  great  development  in  the  Cretaceous  are  in  accordance  with  other 
faunal  and  lithological  features,  indicating  the  deep  water  origin  of  that 


BRACHIOSPON  GID^E. 


19 


formation.  From  this,  it  is  probable  that,  at  an  early  period,  these  orders 
flourished  in  the  deeper  regions  of  littoral  deposits,  and  at  greater  depths. 

While  there  is  no  strong-  reason  for  considering-  the  deposits  contain- 
ing Brachiospongia  as  having  been  formed  in  very  deep  water,  yet  they 
cannot  well  be  considered  as  belonging  to  a littoral  fauna. 

Description  of  Species. 

Brachiospongia  digitata,  Owen. 

Plate  I,  figs.  1,2;  PI.  II,  figs.  1-7  ; PI.  Ill,  figs.  1,  2 ; PI.  IY,  figs.  1-8. 

Sponge  broad  cup-shaped,  or  short  vasiform,  witli  a row  of  arms  (from 
eight  to  twelve  observed)  projecting  outwards  and  downwards  from  the 
periphery  of  the  base.  Osculum  elliptical,  with  the  diameters  usually  in 
the  ratio  of  two  to  three.  Below  the  osculum,  the  walls  of  the  cup,  or 
neck,  are  vertical,  extending  for  a distance  of  from  25  to  40  mm.,  and 
slightly  expanding  below  to  the  origin  of  the  arms. 


Fig.  I. 


Figure  1. — Brachiospongia  digitata;  base  of  the  original  specimen.  One-half  natural  size. 

Base  of  cup  concave,  usually  with  a strong  conical  or  mammiform 
projection  near  the  center,  which  is  the  initial  point  of  the  sponge  (fig.  1). 
The  gastral  side  of  the  base  at  the  initial  point  shows  several  pits,  of 
which  from  three  to  five  have  been  seen  (PI.  II,  fig’.  7). 


20 


BRACHIOSPON  GIDJE. 


The  arms  are  distant  from  each  other  from  one-fourth  to  one-fifth  their 
diameter  at  the  base.  Starting  from  the  origin  of  the  arms,  they  are  nearly 
circular  in  transverse  section,  and  extend  outward  at  right  angles  to  the 
sponge  axis,  or  frequently  upwards,  and  then  are  abruptly  bent  downwards, 
flattened  along  their  outer  faces,  and  terminate  in  a compressed  extremity 
which  is  rarely  bifid.  When  in  a perfect  condition,  the  arms  are  closed  at 
their  distal  ends. 

The  increase  in  the  size  of  the  arms  is  not  altogether  commensurate 
with  the  growth  of  the  sponge,  and  to  compensate  for  the  separation  of  the 
arms,  new  ones  are  added  from  time  to  time.  Plate  I,  figure  2,  shows  a 
wide  space  on  one  side  of  the  longest  arm,  and  as  this  is  about  the 
maximum  size  for  nine-armed  specimens,  further  growth  would  have 
developed  another  arm  at  this  point.  A portion  of  a ten-armed  specimen 
is  shown  in  Plate  II,  figure  3,  in  which  a new  arm  has  just  begun  to  start 
out  from  the  cup,  and  now  appears  as  a large  node,  or  swelling,  between 
the  widely  separated  and  divergent  adjacent  arms.  A still  farther  brachial 
development  is  represented  in  figure  4 of  the  same  plate.  The  specimen 
has  eight  normal  arms  besides  the  central  one  in  the  figure,  which  is  about 
half  grown.  In  the  collections  studied,  comprising  twenty-one  nearly 
entire  specimens,  the  number  of  rays  varies,  with  some  exceptions,  accord- 
ing to  the  size  of  the  individual,  and  is  from  eight  to  twelve.  Further 
research  will  probably  extend  these  limits. 

In  the  following  table,  the  grouping  is  based  upon  the  number  of 
arms.  It  shows  the  variation  in  size,  and  enumerates  the  specimens  in 
each  group. 


Number  of 

Diameter  of  smallest  and  largest  specimens, 

* Number  of 

arms. 

in  inches. 

specimens. 

8 

9± 

1 

9 

34-64 

4 

10 

3f— 9 

9 

11 

5f-ll 

4 

12 

6-10i 

3 

One  of  the  individuals  here  indicated  as  having  ten  arms  is  5^  inches 
in  diameter,  and  shows  in  addition  to  the  ten  fully  developed  rays,  three 


BRACHIOSPONGIDJE. 


21 


nodes,  and  two  branched  arms,  all  spirally  arranged,  beginning  at  the 
initial  point,  and  extending  to  the  oscnlum  of  the  sponge.  A ten-rayed 
example,  having  a diameter  of  6|  inches,  presents  ten  normal  arms,  and 
one  node  representing  an  undeveloped  arm  (PL  II,  fig.  3). 

The  accompanying  wood-cut,  figure  2,  illustrates  an  abnormal  speci- 
men, and  shows  very  clearly  that,  for  specific  distinctions,  little  dependence 
can  be  placed  upon  the  number  and  character  of  the  arms.  On  one  side 
of  the  specimen,  they  are  normally  developed,  while,  on  the  other,  they 
are  bifurcate  and  covered  with  processes  and  large  rounded  protuberances. 


Fig.  2. 


Figure  2. — Brachiospongia  cligitata  ; abnormal  specimen.  One-half  natural  size. 

From  what  is  shown  regarding  the  growth  and  increase  of  the  arms, 
it  is  evident  that  this  feature  is  not  of  sufficient  importance  to  be  used 
as  a basis  for  specific  separation.  With  but  two  or  three  specimens  at 
hand  representing  the  extremes  of  variation,  these  differences  seem  to  be 
important.  Having  numerous  individuals,  however,  representing  different 
stages  and  conditions  of  growth,  we  are  able  to  connect  the  extremes,  and, 
at  the  same  time,  show  the  wide  extent  of  this  mutable  and  mirable  species. 

The  gastral  cavity  is  very  large,  occupying  the  whole  interior  of  the 
cup,  and  extending  nearly  to  the  distal  extremities  of  the  arms. 


6 


22 


BRACHIOSPONGIDiE. 


Some  specimens  which  were  freed  from  the  rock  without  the  use  of 
acids  show  that  the  extremities  of  several  of  the  arms,  and  the  basal  boss, 
were  worn  through  to  the  gastral  cavity  before  they  were  imbedded.  But 
the  present  imperfect  condition  of  many  of  the  weathered  specimens  is  due 
principally  to  breakage,  and  to  the  non-silicification  of  portions  of  the 
sponge  walls. 

Dimensions. — The  smallest  example  observed  (PI.  II,  figs.  5,  6,  7)  has 
nine  arms,  and  measures  45  mm.  in  height.  This  is  somewhat  less  than 
the  original  height,  as  the  neck  is  imperfect,  and  the  extremities  of  the 
arms  broken  off.  The  greatest  diameter  is  80  mm.,  and  the  arms  have  a 
diameter  of  about  16  mm.  at  their  bases.  Two  of  the  largest  individuals, 
preserving  their  full  extent,  measure  about  275  and  330  mm.  respectively, 
in  diameter. 

A restoration  from  fragments  in  the  collection,  based  upon  the  propor- 
tions presented  by  entire  specimens,  indicates  that  the  largest  individuals 
of  this  species  reached  a diameter  of  about  400  mm. 

Brachiospongia  is  among  the  largest  of  the  fossil  Hexactinellida,  and 
ranks  in  this  respect  with  Uplian taenia  and  Cleodictya,  although  they  are 
all  somewhat  exceeded  by  the  recent  genera  Pheronema  and  Poliopogon. 

It  is  interesting  to  note  that  in  the  cavities  of  Brachiospongia  and  in 
the  surrounding  rock  are  numerous  small  spherical  bodies  which  suggest 
the  statement  made  by  Schulze,1  that  in  the  cavities  of  Poliopogon  amadou, 
were  small  spherical  sponges  about  3 mm.  in  diameter,  which  he  considered 
as  the  young  of  that  species.  In  the  present  instance,  however,  these 
bodies  vary  in  size  from  1.5  to  10  mm.,  and  show  a structure  which  is 
characteristic  of  Hindia,  and  the  species  has  been  named  Hindia  parva , by 
Mr.  E.  O.  Ulrich. 

A specimen  of  Brachiospongia  (Plate  III,  fig.  1),  found  by  W.  M. 
Linney  in  the  northern  part  of  Spencer  County,  Kentucky,  in  strata  of  the 
Middle  Hudson  series,  offers  some  points  of  difference  with  those  from 
Franklin  County.  It  is  preserved  in  mudstone,  and  the  parenchyma  of  the 
sponge  has  been  replaced  by  calcite.  The  specimen  measures  235  mm. 


1 Rep.  on  the  Hexactinellida,  p.  257. 


BRACHIOSPON  GID^E. 


23 


in  diameter,  and  has  eight  arms,  whicli  are  constricted  at  their  origin, 
directed  outwards  and  downwards  at  an  angle  of  forty-five  degrees,  and 
are  not  geniculated  as  in  typical  B.  digitata.  The  osculum  is  subcircular, 
and  the  neck  is  campanulate  below.  The  cup,  or  body,  of  the  sponge  is 
comparatively  small.  The  base  is  flat,  and  without  the  initial  projection 
usually  present.  Were  it  not  for  the  great  range  of  variation  shown  in  the 
specimens  from  Franklin  County,  it  would  seem  that  this  form  represented 
a distinct  species.  The  differences  are  probably  due  to  changed  physical 
conditions. 

Spicular  Skeleton. — Rod-like  spicules  were  detected  in  the  matrix 
adjacent  to  the  dermalia,  in  some  of  the  sections  made  for  microscopic 
study.  They  were  without  apparent  regularity,  and  probably  correspond  to 
the  uncinates  or  raphides  in  the  dermal  membranes  of  many  recent  forms. 
As  their  relations  are  uncertain,  they  have  been  omitted  in  the  diagram- 
matic restoration  given  in  Plate  IV,  figure  8. 

The  surface  of  the  sponge  when  well  preserved  presents  a minutely 
papillose  appearance  to  the  unassisted  eye.  The  papillse  are  of  unequal 
size,  irregularly  arranged,  and  distant  1 mm.,  or  less.  When  magnified, 
they  are  seen  to  be  produced  by  an  elevation  of  the  dermal  membrane, 
and  by  five  strong  conical  nodes  occupying  the  center.  It  is  shown  that 
the  latter  belong  to  large  free  hypodermal  pentacts. 

The  dermal  membrane  (PI.  IV,  fig.  1)  is  composed  of  an  exceedingly 
fine  and  irregular  quadrate  mesh  of  four-rayed  spicules,  apparently  fused, 
with  their  centers  distant  from  each  other  from  .1  to  .2  mm.  Occasionally, 
larger  spicules  occur,  which  seem,  with  the  expansion  of  the  surface  due 
to  the  growth  of  the  sponge,  to  develop  eventually  into  the  large  pentacts 
of  the  hypoderm. 

The  hypodermalia  are  less  regularly  arranged  than  the  dermalia,  and 
the  rays  overlap  and  cross  each  other  in  various  directions.  The  proximal 
rays  have  been  observed  to  penetrate  the  parenchyma  to  the  depth  of  2.5 
mm.,  and  the  tangential  rays  reach  a length  of  more  than  1 mm. 

The  parenchyma  varies  in  thickness  with  the  size  of  the  specimen, 
and  in  different  portions  of  the  same  individual.  It  is  thinnest  near  the 


24 


BRACHIOSPONGIDiE. 


extremities  of  the  arms  and  at  the  edge  of  the  cup.  A specimen  80  mm.  in 
greatest  diameter  has  a parenchymal  thickness  of  3 mm.  near  the  ends  of 
the  arms  and  edge  of  the  cup,  and  reaches  a thickness  of  nearly  5 mm. 
near  the  origin  of  the  arms.  The  walls  in  the  central  portion  of  an  arm 
52  mm.  in  diameter  are  10  mm.  in  thickness  laterally,  and  somewhat 
thinner  on  the  distal  and  proximal  sides.  A large  arm  nearly  60  mm.  in 
transverse  diameter  shows  a thickness  of  13  mm. 

The  accompanying  wood-cuts  (figures  3 and  4)  represent  actual 
sections  through  two  arms,  and  show  the  thickness  of  the  parenchyma,  the 
irregular  canals,  and  the  diameter  of  the  gastral  cavity,  in  each.  The 
lower  edge  is  the  flattened  outer  face  of  the  arm. 

Fig.  3.  Fig.  4. 


Figure  3. — Brachiospongia  digitata ; section  across  middle  of  arm. 

Figure  4. — B.  digitata;  section  across  lower  third  of  arm,  from  larger  specimen. 
Both  figures  are  natural  size. 


The  parenchymalia  seem  to  be  all  hexacts,  exhibiting  great  variations 
in  size  and  in  the  development  of  the  rays.  Many  of  them  are  of  about 
the  size  of  the  hypodermalia,  but  much  larger  occur.  Their  principal 
axes  are  usually  parallel  or  vertical  to  the  adjacent  surface  of  the  sponge, 
and  frequently  one  or  more  rays  are  greatly  developed,  and  seem  to  bear 
spines  or  lateral  processes.  In  one  broken  section,  a single  ray  may  be 
traced  for  a distance  of  10  mm.  Other  weathered  specimens  show  many 
similar  elongate  rays  traversing  the  parenchyma.  In  rare  instances,  the 
axial  canals  are  preserved,  and  appear  to  have  been  about  one-third  the 
diameter  of  the  rays. 

No  evidence  is  shown  on  the  exterior  of  the  sponge  of  the  presence  of 
the  interior  canals  or  afferent  pores,  but  on  the  gastral  surface  of  the  walls 


BRACHIOSPON  GIDiE. 


25 


are  numerous  oscula  between  the  rays  of  the  spicules,  often  radially 
arranged,  and  with  larger  circular  depressed  areas  2 to  3 mm.  in  diameter 
marking  the  terminations  of  the  principal  efferent  canals.  The  interior, 
represented  in  horizontal  section,  in  figures  3 and  4 of  Plate  IV,  exhibits 
irregular  cavities  filled  with  crystalline  quartz,  and  cylindrical  vertical 
canals  having  a diameter  of  from  1 to  2 mm.  The  gastral  ends  of  the 
large  canals  are  covered  with  a membrane  in  which  no  spicules  can  be 
detected.  It  is  perforated  by  several  efferent  apertures,  or  oscula.  Also, 
the  walls  of  the  entire  canal  system  appear  to  have  had  a limiting  mem- 
brane, probably  spicular  originally,  but  now  preserved  as  rusty  markings 
in  the  rock. 

The  gastral  membrane  does  not  seem  to  be  as  well  preserved  as  the 
dermal,  nor  are  the  spicules  so  well  differentiated.  It  is  covered  with  a 
layer  of  pentacts  which  are  irregularly  disposed,  and  not  fused  into  a 
connected  mesh.  The  largest  pentacts  measure  about  2 mm.  across,  and 
interspersed  with  them  are  numerous  smaller  spicules.  The  proximal  rays 
of  the  larger  pentacts  extend  into  the  parenchyma,  as  represented  in 
Plate  IV,  figure  7. 

Summary  of  spicular  ancl  internal  characters. — Dermalia  constituting  a 
continuous,  minute,  irregular,  quadrate  mesh  of  four-rayed  spicules.  Hypo- 
dermalia  consisting  of  larger  immersed  pentacts  with  an  elevated  exsert 
node  at  the  base  of  each  tangential  ray,  and  a similar  central  node  repre- 
senting the  atrophied  distal  ray ; proximal  ray  penetrating  the  parenchyma. 

Parenchymalia  comprising  large  and  small  hexacts  with  modified 
rays,  which  are  sometimes  spiniferous.  Gastral  membrane  with  numerous, 
irregularly  arranged,  large  and  small  pentacts  and  tetracts,  which  are  appa- 
rently free ; proximal  rays  long-,  penetrating  the  tissues.  Dermal  pores 
not  defined ; gastral  pores  irregularly  circular  or  oval,  sometimes  disposed 
in  a radial  arrangement.  Gastral  surface  marked  by  circular  depressions 
covered  by  a perforated  membrane,  and  marking  the  terminations  of  the 
main  interior  efferent  canals.  Parenchyma  penetrated  by  numerous 
irregular  canals  and  by  vertical  cylindrical  canals. 


7 


26 


BRACHIOSPONGID^E. 


Geographical  Distribution. — The  specimen  found  by  Dr.  Troost  is 
recorded  as  from  Davidson  County,  Tennessee.  Others  have  been  collected 
in  Mercer  and  Spencer  Counties,  Kentucky.  The  most  prolific  localities 
known  are  in  Franklin  County,  Ky.,  on  Benson  Creek  and  its  tributaries, 
northwest  of  Frankfort,  and  on  Cedar  Run,  two  and  one-half  miles  south. 

Strobilospongia  tuberosa,  sp.  nov. 

Plate  V,  fig.  5 ; Plate  VI,  figs.  3-7. 

The  form  of  the  sponge  is  somewhat  conical,  flattened,  and  deeply 
indented  longitudinally  on  opposite  sides,  from  the  base  to  the  osculum. 
Otherwise,  the  surface  is  covered  with  slightly  pendent,  solid,  tuberose 
extensions  of  the  parenchyma.  ~ Summit  flattened. 

Osculum  irregular,  sinuous ; margin  thin,  sometimes  convoluted. 
Base  broad,  giving  a truncate  appearance  to  the  cup ; penetrated  by  a 
large  mass  of  basalia,  or  root  tuft  of  anchor  spicules,  extending  into  the 
interior  nearly  one-half  the  height  of  the  parenchymal  portion  of  the 
sponge.  In  one  example,  the  bundle  of  anchoring  spicules,  where  it 
emerges  from  the  base,  has  a diameter  of  more  than  one-third  that  of  the 
body  of  the  sponge  above. 

The  principal  specimen  (PI.  VI,  figs.  3,  4,  5)  has  a height  without  the 
root  tufts  of  nearly  80  mm.,  and  the  greatest  diameter  across  the  base  is 
110  mm.  It  is  remarkable  as  preserving  a bud  which  is  still  attached  to 
the  parent  mass,  and  nearly  equals  it  in  size.  The  root  of  the  bud  is  a 
little  smaller,  and  the  lobation  of  the  surface  is  considerably  sharper  and 
more  distinct.  A smaller  individual  70  mm.  high  is  very  irregularly  formed. 
One  side  is  lobed  as  in  the  preceding  example,  and  the  other  is  marked  by 
two  deep  irregular  pits.  A vertical  section  was  made  through  this  example 
revealing  the  extent  of  the  mass  of  basalia  and  of  the  gastral  cavity. 
It  is  represented  in  Plate  VI,  figure  6. 

The  specimens  are  so  thoroughly  silicified  that  the  spicular  structure 
has  been  to  a large  degree  obliterated.  The  cruciform  ends  of  large 
hexactinellid  spicules  can  be  seen  on  some  portions  of  the  surface,  resem- 
bling those  in  similarly  preserved  specimens  of  Brachiospongia  digitata. 


BRACIIIOSPONGIDiE. 


27 


Smaller  dermal  spicules  and  traces  of  a spicular  mesh  can  likewise  be 
detected.  The  parenchymal  canals  are  nearly  vertical  to  the  surface,  and 
measure  .6  mm.  in  diameter.  The  basalia  are  closely  aggregated,  and 
usually  form  a twisted  rope-like  bundle.  The  separate  spicules  are  very 
slender,  not  measuring  more  than  .02  mm.  in  diameter.  The  axial  canals 
are  occasionally  preserved,  and  are  represented  in  Plate  VI,  figure  2. 

The  source  of  the  two  specimens  of  the  species  here  described  is  quite 
uncertain.  They  were  received  accompanied  by  labels  referring  them  to 
the  Hudson  group,  from  Turner’s  Station,  in  northern  Kentucky.  The 
condition  of  preservation  and  enclosing  matrix  bear  much  resemblance 
to  some  specimens  of  Brachiospongia,  whose  location  is  known.  The 
presence,  too,  of  another  species  of  the  same  genus,  and  of  so  many 
similar  masses  of  basalia  in  the  Brachiosponge  bed,  serve  to  point  to  this 
horizon  as  the  probable  source  of  the  species. 

On  Plate  V,  figs.  2,  3,  4,  three  masses  of  basalia  are  shown,  represent- 
ing their  general  features.  The  microscopic  structure  is  delineated  in 
Plate  V,  fig.  5,  a,  b,  and  Plate  VI,  figs.  1,  2.  Ropes  of  spicules,  both  larger 
and  smaller  than  those  illustrated,  were  collected.  One  example  has  a 
diameter  of  110  mm.,  and  others  measure  that  number  of  millimeters  in 
length.  These  numerous  root  tufts  indicate  imperfectly  the  richness  of 
the  original  sponge  fauna  represented  in  these  sediments.  In  an  area  of 
not  more  than  two  square  rods,  on  Cedar  Run,  about  forty  specimens 
were  obtained  on  the  surface  of  the  ground.  They  are  also  common  near 
Bridgeport,  Franklin  County,  and  at  several  places  on  Benson  Creek. 

Similar  masses  of  basalia  have  been  called  Tricholites,  but  it  is  obvious 
that  several  slightly  related  forms  of  sponges  may  have  anchoring  bundles 
of  spicules,  which  are  undistinguishable  from  each  other,  and  that  specific, 
or  even  generic  characters  are  seldom  impressed  on  the  root  tufts.  The 
genera  Leptomites,  Hyalostelia,  and  Acestra,  represent  varieties  of  basalia 
for  which  the  sponge  proper  has  not  been  discovered.  Recently,  root 
spicules  were  described  for  the  genus  Protospongia,  by  Sir  Wm.  Dawson 
and  Dr.  Geo.  J.  Hinde,1  but  they  do  not  form  a massive  bundle. 

1 Canadian  Record  of  Science,  Montreal : April,  1S88. 


28 


BRAC  H10SP0N  GID^E. 


Distribution. — The  two  specimens  of  8.  tuberosa  bear  the  label 
“ Turner’s  Station,  Ky.”  Numerous  masses  of  basalia  have  been  found 
in  and  above  the  Brachiosponge  bed  on  Benson  Creek  Cedar  Run,  at 
Frankfort,  Franklin  County,  and  at  Lexington,  Fayette  County,  Kentucky. 
Under  the  name  Tricholites  typicalis,  Mr.  E.  0.  Ulrich  has  catalogued 
similar  bundles  of  spicules  from  the  tops  of  the  hills  at  Cincinnati,  Ohio. 

Steobilospongia  aueita,  sp.  nov. 

Plate  V,  tig.  1. 

The  only  example  of  this  species  known  is  a compressed  cup-shaped 
specimen  found  associated  with  Beachiospongia,  on  Benson  Creek.  The 
summit  and  base  are  both  imperfect,  and  the  special  features  of  these  por- 
tions cannot  be  described.  There  is  a flattened,  depressed  area  down  the 
center  of  the  sides,  which  is  without  ornamentation.  The  specimen  pre- 
serves five  concentric  imbricating  rows  of  auriculate  pendent  extensions  of 
the  parenchyma,  some  of  which  are  so  closely  oppressed  to  the  cup  that 
the  underlying  tissues  are  excavated  for  their  reception.  In  general,  these 
expansions  appear  to  be  solid,  but  several  show  that  the  gastral  cavity 
extends  into  them  for  a short  distance. 

The  microscopic  structure  is  no  better  preserved  than  in  the  pre- 
ceding species,  and  the  spicular  skeletons  of  both  agree  in  all  the  features 
which  can  be  observed. 

The  specimen  lias  a height  of  136  mm.,  and  a maximum  diameter 
through  the  center  of  138  mm.  The  latter  dimension  is  somewhat  greater 
than  normal,  on  account  of  the  compressed  condition  of  the  sponge.  It  is 
completely  silicified,  and  preserved  in  a condition  similar  to  the  majority 
of  the  specimens  of  Beachiospongia. 

As  compared  with  S.  tuberosa , this  species  reaches  a greater  size  and 
is  more  robust,  the  parenchymal  expansions  are  much  larger,  pointed 
directly  downwards,  and  more  regularly  arranged  in  concentric  rows. 

Distribution. — From  the  Brachiosponge  bed  on  Benson  Creek,  Franklin 
County,  Kentucky. 


PLATE  I. 


PLATE  I. 

Brachiospongia  digitata. 

Page  19. 

Fig.  1. — Original  specimen  ; lateral  view.  Natural  size. 

Fig.  2. — The  same  ; seen  from  above.  Natural  size.  Davidson  County , Term. 
Original  in  Yale  University  Museum. 


F.  Berger,  del. 


L.  Schierholz,  lith. 


BRACHIOSPONGIDAl  . 


PLATE  I 


PLATE  II. 


PLATE  II. 


Brachiospongia  digitata. 

Page  19. 

Fig.  1.— Side  view  ; showing  full  extent  of  arms. 

Fig.  2. — The  same  ; showing  section  through  cup,  and  openings  into  gastral  cavities  of 
arms.  Natural  size,. 

Fig.  3. — Side  view  of  imperfect  specimen  ; showing  initial  point  in  growth  of  one  arm, 
which  here  appears  as  a swelling,  or  node.  One-half  natural  size. 

Fig.  4. — Another  specimen  ; exhibiting  one  arm  apparently  about  half  grown.  One-half 

natural  size. 

Figs.  5,  6,  7. — Lateral,  bottom,  and  top  views  of  smallest  specimen  observed.  Natural 
size. 

Brachiosponge  bed.  Franklin  County.  Ky. 

Originals  in  Yale  University  Museum. 


BRACHIOSFONGIDAI 


PLATE  II 


3 


i vj,ArrK  hi. 


9 


PLA TJE  III. 


Brachiospostgia  digitata. 

Page  19. 

Fig.  1. — Top  view  of  eight-armed  specimen  mentioned  on  page  22.  The  parenchyma  has 
been  partially  exfoliated,  and  the  cast  of  the  interior  is  exposed  in  several 
places.  One-half  natural  size.  Middle  Hudson.  Spencer  County , Ky. 

Fig.  2. — Lower  side  of  large  twelve-armed  specimen,  in  the  collection  at  the  State 
Museum,  Frankfort,  Ky.  One-half  natural  size.  Braehiosponge  bed. 
Franklin  County,  Ky. 

Original  of  figure  1 in  Yale  University  Museum. 


2#(S 


BPACHIOSPONGIDAI 


PLATE  III 


F.  Berger,  del. 


L.  Schiertiolz,  lith. 


PLATE  IV. 


PLATE  IV. 


Brachiospongia  digitata. 

Page  23. 

Fig.  1. — Outer  surface  of  sponge  ; showing  dermal  spicular  mesh  and  exsert  nodes  on 
rays  of  hypodermal  pentacts.  X 20. 

Fig.  2. — Section  representing  large  hypodermalia  after  removal  of  dermal  mesh,  x 20. 

Fig.  3. — Horizontal  section  of  interior  of  parenchyma.  X 20. 

Fig.  4. — Horizontal  natural  section  from  broken  specimen,  x 4. 

Fig.  5. — Subgastral  skeleton  ; showing  large  spicules  and  ends  of  efferent  canal  system. 

The  circular  depressions  represent  ends  of  vertical  cylindrical  canals.  X 10. 

Fig.  6. — Inner,  or  gastral,  surface.  X 20. 

Fig.  1. — Vertical  section  through  parenchyma  with  small  portion  of  adhering  matrix  on 
dermal  side,  x 20. 

Fig.  8. — Restored  vertical  section,  combining  characters  represented  in  the  preceding 
figures,  which  were  drawn  from  actual  specimens.  X 10. 

Originals  in  Yale  University  Museum. 


BRACHIOSPONGID/B  . 


PLATE  IV. 


C.E. Beecher,  del. 


L.  Schierhoiz,  lim. 


PLATE  V. 


10 


PLATE  V. 

Strobilospongia  aurita. 

Page  28. 

Fig.  1 . — Lateral  view  of  type  specimen.  Natural  size.  Brachiosponge  bed.  Franklin 
County , Iiy. 


Basalia. 

Page  27. 

Figs.  2,  3,  4. — Three  masses  of  anchor  spicules  presenting  characteristic  features. 
Natural  size.  Brachiosponge  bed.  Franklin  County , Ky. 

Fig.  5. — a.  Longitudinal  section  of  small  portion  ; showing  size  and  disposition  of 
basalia.  X 25. 

b.  Transverse  section  from  same  specimen,  x 25. 

c.  Section  of  small  fragment  of  parenchyma  of  Strobilospongia  tuber osa ; 

showing  two  imperfectly  preserved  hexactinellid  spicules,  x 25. 

Originals  in  Yale  University  Museum. 


BRACHIOSPONGIDiR,  . 


PLATE  V 


F.  Berger,  del 


L.  Schier’aolz,  lith. 


PLATE  V I . 


PLATE  VI. 

B ASALIA. 


Page  27. 

Fig.  1. — Longitudinal  section  of  fragment.  X 7o. 

Fig.  2. — Transverse  section  ; showing  diameter  of  spicules  and  axial  canals.  X 70. 
Brachiosponge  bed.  Franklin  County , Ky. 

Strobilospongia  TUBEROSA. 

Page  26. 

Fig.  3. — Lateral  view  ; showing  parent  sponge  at  the  right,  and  attached  bud  on  the  left 
with  its  separate  bundle  of  basalia.  Natural  size. 

Fig.  4. — Basal  view  of  same  specimen. 

Fig.  5.— Side  view  of  bud  ; showing  strong  lobation  of  surface. 

Fig.  6. — Small  example,  cut  longitudinally  through  the  center  ; exhibiting  extent  of 
bundle  of  basalia,  gastral  cavity,  and  variable  thickness  of  parenchyma. 

Natural  size. 

Fig.  7. — The  same  ; showing  external  form  of  sponge,  and  narrow  and  sinuous  aperture 
at  summit. 

Both  specimens  of  this  species  are  recorded  as  from  the  Hudson  group  at 
Turner’s  Station,  Ky. 

Originals  in  Yale  University  Museum. 


B R AC  HI  O S P O NG  IDTL 


PLATE  VL 


F.  Berger,  del. 


L.  Schierholz,  lith. 


X70 

6 


X70 


Date  Due 

Form  335— 15M— 7-36— S 

